Assessing the performance of a surface washing agent for oil removal from sand in cold environments

Persistent oil contamination along coastlines can be treated by surface washing agents (SWAs), while low-temperature conditions can significantly impact the effectiveness of SWAs in oil removal. This study investigates the oil removal performance of a commercial SWA for oiled shoreline sand in cold-region environments. Batch oil removal tests were conducted to explore the effectiveness of this SWA under different conditions (i.e., SWA concentration, salinity, humic acid concentration, and kaolinite concentration). The results show that the SWA exhibited high oil removal efficiency even under cold conditions. Higher SWA and kaolinite concentrations were beneficial for oil removal, but humic acid had negative effects on the oil removal performance. In terms of salinity, the oil removal efficiency of SWA first increased (peaking at 1.0 wt%) and then gradually decreased as the salinity increased from 0 to 3.5 wt%. Factorial analysis further revealed that salinity significantly modulates the influence of SWA concentration on oil removal from shoreline sand. This work indicates the great potential of SWA as a spill treating agent for shoreline cleanup, especially in cold regions with increasing risks of oil spills resulting from climate change.